Busted rocker shaft (pics), need suggs...

[SS_Sean]

Yup, raced the GN at the track a couple weeks ago...I was well on my way to a 13 second pass on only 15 pounds of boost. between the 330 and 1/8 I lost power and new something was wrong so I backed out of it and coasted her in. I had a ticking noise on the driver's side valve train and figured I collapsed a lifter or bent a push rod. What I found I was not expecting.

I finally got a chance to pull the driver's side valve cover and found the forward-most rocker had busted right off the shaft. It lifted so hard it bent the el-cheapo grade five bolts the previous owner used on the hold-downs. I may have over-revved the motor, though my chip indicates the redline is set at 6000. I'm not sure how the rocker could have lifted so hard like that unless I did over-rev the motor.

Any thoughts?

What rocker assembly would you guys suggest? My mods are in my link. Be advised my next upgrade is an alky control kit, and I will be laying more boost at it...maybe 20-25 depending on the tune.

Thanks.

 

[Boost231]

just get some HD shafts if you dont want to spend 500 bucks on roller rockers.

 

[bsdlinux]

just get some HD shafts if you dont want to spend 500 bucks on roller rockers.

Agreed. Roller rockers are overkill for a stock headed motor.

BTW: anyone know what usually will cause a rocker shaft to break??

 

[1BADTT]

Maybe this will provide some answers:

RJC Rocker Shaft Braces

 

[SS_Sean]

That's exactly what happened...it lifted the shaft into the head of the hold-down-nut, and both let go. Those supports look good. The thing is, can a stock shaft with those hold downs work for my level of performance? Do I need to go to an HD set? I don't believe I need roller at this point, but I could be wrong?

 

[bsdlinux]

Maybe this will provide some answers:

RJC Rocker Shaft Braces

Yes. But RJC quotes that bigger cams and higher spring pressures can cause breakage. I've seen those shaft problems on unopened motors before... that is the answer I'm after.

That's exactly what happened...it lifted the shaft into the head of the hold-down-nut, and both let go. Those supports look good. The thing is, can a stock shaft with those hold downs work for my level of performance? Do I need to go to an HD set? I don't believe I need roller at this point, but I could be wrong?

Get some HD shafts or another stock one and use the RJC blocks and be done with it. You go into the motor and get a roller cam then maybe you upgrade at that point.

 

[1BADTT]

Good ETs in sig...

If ur running those times in ur sig , I'd use rollers. It'll free up some more hp & less friction (stress). Just my $.02 !

 

[SS_Sean]

The time in my sig is for the malibu.

 

[bsdlinux]

SS Sean .. what are your goals for the GN??

 

[1BADTT]

The time in my sig is for the malibu.

10-4. Brace it

 

[scot w.]

Sean i have some used stock shafts i would sell you if you need them and i would get those caps from RJC also. For what it's worth, a good freind of mine is running 26lbs of boost with razors alky kit. he also has stock heads with stock rocker shafts with a TA-49 turbo.

 

[SS_Sean]

The complete rocker shaft assembly for both sides looks to be $99.70 from Postons. You can't been that. So, with the RJC caps I might just get out of this on the cheap. The one pushrod is bent, but I will go ahead and replace all twelve.

 

[SS_Sean]

SS Sean .. what are your goals for the GN??

The goal is 12 seconds and streetable. All the pieces are there, I just have to get the boost up there a little and tune.

 

[jasjamz]

Maybe this will provide some answers:

RJC Rocker Shaft Braces

So you only need 4 to to the end bolts? Do they come with longer bolts or do the stock ones work?

 

[broke1]

Roller rockers are overkill for a stock headed motor.

Maybe on your stock headed motor,not mine.

Lots of people say stock cam this and stock cam that.Truth is,youll pickup a buttload of tq with a small roller cam and roller rockers,even with stock heads.....

My $.02.

 

[bsdlinux]

Maybe on your stock headed motor,not mine.

Lots of people say stock cam this and stock cam that.Truth is,youll pickup a buttload of tq with a small roller cam and roller rockers,even with stock heads..... My $.02.

Good answer .. my answer is... Ed Brewer .. nuff said :biggrin:

 

[broke1]

My stock headed ta61 car made 520tq @ 19psi with 17 dg of timing.Nuff said

 

[Boost231]

You will use the stock bolts. i have been running rjc rocker braces since they have came out. i have all 6 but now he just sales them as a set of 4 since the other 2 are really not need. i have gone mid 12's with stock shafts and with his supports with no problems. I have run 25+ pounds of boost on them as well and havent had a problem.

 

[insane6]

When that happen to mine I bought the solid shaft from Fullthrottle, very nice piece.

 

[Boost231]

cant go wrong with the solid shafts. But if you can get a set of stockers for real cheap and buy the supports you should be good.